Tropical Grasslands (1989) Volume 23, 9297
RESPONSES TO INOCULATION WITH ROOT-NODULE BACTERIA BY LEUCAENA LEUCOCEPHALA IN SOILS OF N.E. THAILAND
J. HOMCHAN1, R.A. DATE2 and R.J. ROUGHLEY3
1Department of Soil Science, University of Khon Kaen, Khon Kaen, Thailand.
The responses of Leucaena leucocephala cv. Cunningham to inoculation with a highly effective strain of root-nodule bacteria were investigated on Korat, Namphong and Yasothon soils, the main soil series of N.E. Thailand. For the first 20 weeks TAL1145str always formed > 97% of the nodules on all 6 sites but by 64 and 72 weeks the proportion declined to 50, 80 or 90% at 3 of the 4 sites tested. At these 3 sites it invaded uninoculated plots forming 47 to 81 % of the nodules. It failed to spread on the Yasothon soil. Plant dry weight was increased by inoculation and by nitrogen at 5 of the 6 sites by 20 weeks. The site that failed to respond to inoculation was different to that for nitrogen. By 64 or 72 weeks, differences in plant height, plant dry weight, seed yield and nodule dry weight resulting from inoculation were no longer significant. In the nitrogen treatment there was a trend towards higher values for all of these parameters but only that for seed yield was significant.